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United States Patent |
5,307,339
|
Tanaka
|
April 26, 1994
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Translating apparatus for an optical pickup device
Abstract
A translating apparatus for an optical pickup device comprises an optical
pickup device for radiating an optical disc with a light beam, a rack
member attached to the optical pickup device, a supporting device having a
guide portion for guiding the optical pickup device along a diametrical
direction of the optical disc, and a translating device including a gear
attached to the supporting device and meshed with the rack member, a drive
apparatus for rotating the gear and a releasing mechanism for releasing
the gear and the rack from being meshed with each other when the optical
pickup device is translated beyond a predetermined translating range.
Inventors:
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Tanaka; Kazuhiro (Tokyo, JP)
|
Assignee:
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Sony Corporation (Tokyo, JP)
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Appl. No.:
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932646 |
Filed:
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August 20, 1992 |
Foreign Application Priority Data
Current U.S. Class: |
720/664; 74/89.17 |
Intern'l Class: |
G11B 019/00 |
Field of Search: |
369/215,219,244,220
74/89.17
|
References Cited
U.S. Patent Documents
4152728 | May., 1979 | Camerik | 358/128.
|
4686665 | Aug., 1987 | Kamoshita | 369/215.
|
4807219 | Feb., 1989 | Kyohya | 369/220.
|
5008876 | Apr., 1991 | Nakagishi | 369/219.
|
5025371 | Jun., 1991 | Heinrich | 369/215.
|
5119362 | Jun., 1992 | Yanagisawa | 369/215.
|
Foreign Patent Documents |
29465 | Feb., 1986 | JP | 369/215.
|
2080599A | Feb., 1982 | GB.
| |
Other References
Patent Abstracts of Japn, vol. 9, No. 86 (P-349)(1809), 16 Apr. 1985 &
JP-A-59 215 081 (Olympus Kogaku Kogyo K.K.), 3 Dec. 1984.
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Primary Examiner: Bertsch; Richard A.
Assistant Examiner: McAndrews, Jr.; Roland G.
Attorney, Agent or Firm: Shaw, Jr.; Philip M.
Claims
What is claimed is:
1. A translating apparatus for an optical pickup device comprising:
(a) optical pickup means for radiating an optical disc with a light beam;
(b) a rack member attached to said optical pickup means;
(c) supporting means having a guide portion for guiding said optical pickup
means along a diametrical direction of the optical disc;
(d) translating means including a gear attached to said supporting means
and meshed with said rack member, drive means for rotating said gear and
releasing means for releasing said gear and said rack member from being
meshed with each other when said optical pickup means is translated beyond
a predetermined translating range; and
(f) an attaching member for attaching said translating means to said
supporting means so that said translating means become freely rotatable
relative to said supporting means and spring-biasing means for
spring-biasing said translating means in a direction in which said
translating means is engaged with said rack member.
2. The translating apparatus for an optical pickup device according to
claim 1, wherein said releasing means rotates said translating means in a
direction in which said translating means is moved away from said rack
member on the basis of a drive force from said driving means.
3. The translating apparatus for an optical pickup device according to
claim 2, wherein said releasing means includes a worm gear and a worm
wheel for transmitting the drive force from said drive means to said gear.
4. A translating apparatus for an optical pickup device comprising:
(a) optical pickup means for radiating an optical disc with a light beam;
(b) a rack member attached to said optical pickup means;
(c) supporting means having a guide portion for guiding said optical pickup
means along a diametrical direction of the optical disc;
(d) translating means including a gear attached to said supporting means
and meshed with said rack member, drive means for rotating said gear and
releasing means for releasing said gear and said rack member from being
meshed with each other when said optical pickup means is translated beyond
a predetermined translating range; and
(e) attaching means for attaching said translating means to said supporting
means so that said translating means becomes freely rotatable relative to
said supporting means, wherein said attaching means further includes
spring-biasing means for spring-biasing said translating means in a
direction in which said translating means is engaged with said rack
member.
5. The translating apparatus for an optical pickup device according to
claim 4, wherein said attaching means includes a fulcrum as a rotating
start point for said translating means and restricting means for
restricting a rotating amount of said translating means.
6. The translating apparatus for an optical pickup device according to
claim 4, wherein said releasing means rotates said translating means in a
direction in which said translating means is moved away from said rack
member on the basis of a drive force from said driving means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to translating apparatus for an optical
pickup device applicable to optical disc players such as an optical video
disc player or the like and, more particularly, to a mechanism that
translates an optical pickup device in the inner or outer diametrical
direction of an optical disc, i.e.., a so-called rack and pinion system
translating apparatus for an optical pickup device.
2. Description of the Related Art
Conventional optical pickup devices used in an optical video disc player,
for example, operate to radiate a laser beam on a signal recording surface
of an optical disc that is rotated at high speed. Then, the radiated laser
beam that has been reflected on the optical disc is detected by a
photodetector to thereby optically read out an information recorded on the
signal recording surface of the optical disc. The information thus read
out from the signal recording surface of the optical disc is converted
into an electrical signal and thereby reproduced as an image or sound. The
above optical pickup device is usually translated in the diametrical
direction of the optical disc while the laser beam from the optical pickup
device is tracing the tracks on the signal recording surface of the
optical disc.
A swing arm system, a rack and pinion system, a belt drive system or linear
motor system are known as a method of translating the optical pickup
device in the diametrical direction of the optical disc. Of these systems,
according to the translating method of the rack and pinion system, a rack
is provided on the optical pickup device side and the rack is geared and
moved by a pinion (drive gear) that is rotated by a feed motor in a
decelerated fashion, whereby the optical pickup device is translated in
the diametrical direction of the optical disc (see Japanese Published
Utility Model Publication No. 2-29573, Japanese Laid-Open Utility Model
Publication No. 58-62486, etc.).
However, the conventional optical pickup device translating apparatus of
the rack and pinion system has a defect such that the optical pickup
device is translated at high speed, i.e., the optical pickup device is
recklessly translated by the feed motor to which an overcurrent is applied
due to the influence of an electric circuit or the like in a drive system,
for example, during the time translating apparatus is in adjustment. If
the optical pickup device is translated recklessly, then the optical
pickup device hits the chassis side at the innermost or outermost
peripheral position of the optical disc so that the rack or pinion is
damaged by an impulsive force applied thereto.
In order to protect the rack or pinion from being damaged, it has long been
customary to avoid the impulsive force of the optical pickup device by
using a shock absorbing material. However, if an impulsive force is beyond
a certain limit, then the shock absorbing action of the shock absorbing
material becomes ineffective, which unavoidably causes the rack or pinion
to be damaged.
As another proposal for protecting the rack or pinion from being damaged,
it has been customary to change the material of the rack or pinion or to
enlarge the size of assembly parts so that the rack or pinion can endure
the impulsive force. In this case, there is a limit in strength. Further,
in a motor using a worm as an output shaft, when the optical pickup device
is shocked, a worm and a worm wheel are locked so that an inverting
operation of the driving system is disabled.
On the other hand, in the optical pickup device translating method of the
belt transport system, the impulsive force of the optical pickup device is
transmitted to the belt itself so that the belt is deteriorated earlier
because the belt is extended. Also, assembly members such as a pulley or
the like are needed in association with the belt, which increases the
number of assembly parts.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an improved
translating apparatus for an optical pickup device in which the aforesaid
shortcomings and disadvantages encountered with the prior art can be
eliminated.
More specifically, it is an object of the present invention to provide a
translating apparatus for an optical pickup device in which a driving
system such as a rack, a pinion or the like can be prevented from being
damaged when an optical pickup device is translated recklessly.
It is another object of the present invention to provide a translating
apparatus for an optical pickup device in which a motor can be prevented
from being disabled to rotate in the reverse direction when a gear is
locked.
It is a further object of the present invention to provide a translating
apparatus for an optical pickup device which is high in reliability.
According to an aspect of the present invention, there is provided a
translating apparatus for an optical pickup device which comprises an
optical pickup device for radiating an optical disc with a light beam, a
rack member attached to the optical pickup device, a supporting device
having a guide portion for guiding the optical pickup device along a
diametrical direction of the optical disc, and a translating device
including a gear attached to the supporting device, the gear being meshed
with the rack member, a drive apparatus for rotating the gear and a
releasing mechanism for releasing the gear and the rack member from being
meshed with each other when the optical pickup device is translated beyond
a predetermined translating range.
In accordance with the thus arranged apparatus for an optical pickup
device, if the drive gear is rotated at high speed by an overcurrent
applied to the motor and the optical pickup device is recklessly
translated via the rack meshed with the gear in the innermost or outermost
periphery of the optical disc so that the rack strikes at its end portion
the chassis, then the drive gear meshed with the rack is stopped from
rotating. Consequently, by a reaction force generated from an output gear
so as to rotate the drive gear, the motor base plate having the motor
mounted thereon is rotated about the engagement portion toward the outside
of the rack against the spring force of the spring member, whereby the
drive gear is released from being meshed with the rack and made free.
Then, when the drive gear is released from the rack, the drive gear is
moved toward the rack by the spring force of the above spring member via
the motor base plate and meshed with the rack again. In this case,
however, the drive gear is repeatedly released from the rack by the
rotation in the outside of the motor base plate so that the drive gear is
idled, thereby preventing the rack and the drive gear from being damaged
when locked.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the objects, features, and advantages of the
invention can be gained from a consideration of the following detailed
description of the preferred embodiment thereof, in conjunction with the
figures of the accompanying drawings, wherein:
FIG. 1 is fragmentary cross-sectional plan view of a translating apparatus
for an optical pickup device according to an embodiment of the present
invention;
FIG. 2 is a fragmentary cross-sectional plan view of a motor and a worm
wheel of the translating apparatus for an optical pickup device according
to the embodiment of the present invention;
FIG. 3 is a diagram used to explain operation of the translating apparatus
when an optical pickup is translated normally;
FIG. 4 is a diagram used to explain operation of the translating apparatus
when the optical pickup device is recklessly translated toward the
innermost periphery of the optical disc; and
FIG. 5 is a diagram used to explain operation of the translating apparatus
when the optical pickup device is recklessly translated toward the
outermost periphery of the optical disc.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A translating apparatus for an optical pickup device according to an
embodiment of the present invention will hereinafter be described with
reference to the drawings.
FIG. 1 of the accompanying drawings is a plan view showing an optical
pickup device used in an optical video disc player and a translating
apparatus for the optical pickup device according to the present invention
in a fragmentary cross-sectional fashion.
As shown in FIG. 1, an optical pickup device depicted by reference numeral
1 is supported on a slider 2. The slider 2 can be translated together with
the optical pickup device 1 because the slider 2 itself is moved along a
guide rail 4 whose respective ends are supported to a pickup supporting
frame member 3 serving as a chassis and an engagement portion 2a provided
on the slider 2 also is moved along a rail 3 of the chassis in the inner
and outer diametrical direction of an optical disc 25.
The optical pickup device 1 comprises an objective lens 5 for converging a
laser beam emitted from a semiconductor laser serving as a light source on
a signal recording surface (not shown) of the optical disc 25, a
photodetector 6 for detecting a laser beam reflected on the signal
recording surface of the optical disc 25, a biaxial actuator (not shown)
for servo-controlling the objective lens 5 in the focusing and tracking
directions and an optical system (not shown) for introducing the laser
beam emitted from the semiconductor laser into the objective lens 5 and
which also introduces the laser beam incident via the objective lens 5 and
reflected on the signal recording surface of the optical disc 25 into the
photodetector 6. The optical pickup device 1 includes on the side of the
slider 2 opposing the optical disc 25 a tilt detector 7 which detects an
inclination, i.e., skew of the optical disc 25. On the basis of an output
signal from the tilt detector 7, the servo operation is effected so that
one end of the pickup device support frame 3 is used as a fulcrum, its
other end is moved toward and away from the optical disc surface and
inclined relative to the optical disc surface, thereby adjusting the skew
angle of the optical disc in order to allow the laser beam to become
perpendicularly incident on the signal recording surface of the optical
disc along an optical axis of the optical pickup device 1, i.e., objective
lens 5.
A rack 8 is unitarily molded with the slider 2 in parallel to the guide
rail 4 and a rack gear 9 is formed on the outer surface of the rack 8
along the longitudinal direction of the rack 8. The rack 8 is slid
together with the slider 2 by a translating apparatus 10, which will be
described below, thereby translating the optical pickup device 1.
As illustrated in FIG. 1, the translating apparatus 10 comprises a motor 11
serving as a drive source and a worm wheel 12 having a drive gear rotated
by a drive force of the motor 11 to transport the rack 8 in a gear
fashion. The arrangement of the translating apparatus 10 will be described
more fully below.
The motor 11 is supported on a motor base plate 13, and the motor base
plate 13 is pivotally supported by a mount 14 attached to the
aforementioned pickup device support frame member 3 and which is
horizontally elongated toward the front side of the rack 8.
More specifically, as shown in FIG. 1, first and second elliptic apertures
15, 16 of different lengths are each bored through the motor base plate 13
in an opposing relation to each other in an arcuate fashion. First and
second elliptic apertures 15, 16 are respectively rotatably supported by
first and second shaft pins 17, 18 projected from the mount 14, thereby
forming pivot portions. As shown in FIG. 2, a rotary shaft 12b of the worm
wheel 12 is pivotally supported to a support base plate 13a unitarily
elongated from the lower side of the motor base plate 13. The worm wheel
12 has a drive gear 12a coaxially rotatable therewith and whose diameter
is smaller than that of the worm wheel 12. The worm wheel 12 is meshed
with a worm 20 provided on an output shaft 19 of the motor 11, and the
drive gear 12a is meshed with the rack teeth 9 of the rack 8 (see FIG. 2).
As to the motor base plate 13 and the mount 14, a first spring 21 is
extended between hook portions 13b and 14a formed on both the motor base
plate 13 and the mount 14 in the outside of the elliptic aperture 16. An
outer end (lower end in FIG. 1) of the second elliptic aperture 16 is
engaged with the second shaft pin 18 by a spring force of the first spring
21. Also, the worm 20 is spring-biased by the first spring 21 in the
direction in which it is meshed with the worm wheel 12. Further, in the
outside of the first elliptic aperture 15, a second spring 22 is extended
between a supporting member 13c formed on the motor base plate 13 and the
pickup device supporting frame member 3. Accordingly, an outer end (lower
end in FIG. 1) of the first elliptic aperture 15 is engaged with the first
shaft pin 17 by a spring force of the second spring 22. Also, the drive
gear 12a of the worm wheel 12 is spring-biased toward the rack teeth 9
side.
Referring to FIGS. 3 to 5, let us describe the operation of the translating
apparatus when the optical pickup device is normally translated and the
protecting operation of the translating apparatus when the optical pickup
device is translated recklessly in the optical pickup device translating
apparatus thus arranged.
Initially, the operation of the translating apparatus when the optical
pickup device is thereby translated normally will be described below.
FIG. 3 of the accompanying drawings is a plan view used to explain a normal
translating operation of the optical pickup device 1.
As shown in FIG. 3, the worm 20 provided on the motor output shaft 19 is
spring-biased by the spring force of the first spring 21 and then meshed
with the worm wheel 12, whereas the drive gear 12a is spring-biased by the
spring force of the second spring 22 and then meshed with the rack teeth 9
of the rack 8. Accordingly, in this state, the drive force of the motor 11
rotates the worm wheel 12 meshed with the worm 20 formed on the output
shaft 19 of the motor 11 to transport the rack teeth 9 meshed with the
drive gear 12a, thereby translating the rack 8. Thus, the optical pickup
device 1 is translated together with the slide 2 in the inner and outer
diametrical direction of the optical disc not shown.
A protecting operation of the translating apparatus of the present
invention when the optical pickup device 1 is recklessly translated in the
innermost or outermost periphery of the optical disc will be described
next with reference to FIGS. 4 and 5. FIG. 4 is a plan view used to
explain the protecting operation of the translating apparatus when the
optical pickup device 1 is translated toward the innermost periphery side
of the optical disc, whereas FIG. 5 is a plan view used to explain the
protecting operation of the translating apparatus when the optical pickup
device 1 is translated toward the outermost periphery side of the optical
disc.
With reference to FIG. 4, let us first describe the protecting operation of
the translating apparatus when the optical disc 1 is recklessly translated
toward the innermost peripheral side of the optical disc. In the stage in
which the translating apparatus is adjusted on the maker side, when an
overcurrent is flowed to the motor 11 due to the influence of the electric
circuit or the like of the drive system, for example, causing the optical
pickup device 1 to be translated at high speed, the optical pickup device
1 is recklessly translated to the innermost peripheral position of the
optical disc so that the end portion of the rack 8 strikes the pickup
device supporting frame member 3 (not shown in FIG. 4) and the rotation of
the drive gear 12a meshed with the rack teeth 9 is stopped. As a result,
by a reaction force generated from the worm 20 meshed with the worm wheel
12 so as to rotate the worm wheel 12 in the clockwise direction (direction
shown by an arrow a in FIG. 4), the motor base plate 13 supporting the
motor 11 is rotated about the second shaft pin 18 from the horizontal
state shown in FIG. 3 against the spring force of the second spring 22
such that the first elliptic aperture 15 engaged with the first shaft pin
17 is moved from the outer end to the inner end. At the same time when the
motor base plate 13 is operated as described above, the supporting base
plate 13a unitarily formed with the motor base plate 13 is rotated in the
direction shown by an arrow b in FIG. 4 in unison with the motor base
plate 13, whereby the drive gear 12a is released from being meshed with
the rack teeth 9 and made free as shown in FIG. 4. When the drive gear 12a
has released from the rack teeth 9, the supporting base plate 13a and the
worm wheel 12 are moved toward the rack 8 by the spring force of the
second spring 22 that spring-biases the motor base plate 13 toward the
rack 8 side, thereby bringing the drive gear 12a and the rack teeth 9 into
a meshed state again. In this case, as described above, the drive gear 12a
is repeatedly released from the track teeth 9 each time the motor base
plate 13 is rotated by the reaction force of the worm 20. Consequently,
the drive gear 12a is idled and hence the teeth of the rack teeth 9 and so
on can be prevented from being damaged by the locked state between the
drive gear 12a and the rack 8.
The protecting operation of the translating apparatus when the optical
pickup device 1 is recklessly translated toward the outermost peripheral
side of the optical disc will be described with reference to FIG. 5.
When the optical pickup device 1 is recklessly translated to the outermost
peripheral position of the optical disc and strikes the pickup device
supporting frame member (not shown in FIG. 5), the drive gear 12a meshed
with the rack teeth 9 is prevented from rotating. As a consequence, by a
reaction force generated from the worm 20 so as to rotate the worm wheel
12 in the counter-clockwise direction (direction shown by an arrow c in
FIG. 5), the motor base plate 13 supporting the motor 11 is rotated about
the first shaft pin 17 from the horizontal state shown in FIG. 3 such that
the second elliptic aperture 16 engaged with the second shaft pin 18 is
moved from the outer end to the inner end. At the same time when the motor
base plate 13 is operated, the supporting base plate 13a unitarily formed
with the motor base plate 13 is rotated in the direction shown by an arrow
d in FIG. 5 in unison with the motor base plate 13, whereby the drive gear
12a is released from being meshed with the rack teeth 9 and made free as
shown in FIG. 5. When the drive gear 12a has released from the rack teeth
9, the drive gear 12a is moved toward the rack 8 together with the
supporting base plate 13a by the spring force of the first spring 22,
thereby bringing the drive gear 12a and the rack teeth 9 into a meshed
state again. However, similarly as described above, the drive gear 12a is
repeatedly released from being meshed with the rack teeth 9 each time the
motor base plate 13 is rotated by the reaction force of the worm 20,
whereby the drive gear 12a is idled together with the worm wheel 12.
Therefore, the teeth of the rack teeth 9 and so on can be prevented from
being damaged by the locking between the drive gear 12a and the rack 8
similarly as described before.
As described above, according to the optical pickup device translating
apparatus of the present invention, even when the optical pickup device is
recklessly translated by the overcurrent applied to the motor 11 due to
the influence of the electric circuit or the like in the driving system at
the adjustment stage of the translating apparatus and strikes the chassis,
the drive gear 12a can be readily released from being engaged with the
rack 8. Therefore, the rack 8 and the drive gear 12a can be protected from
being damaged.
Further, according to the optical pickup device translating apparatus of
the present invention in which the worm 20 is provided on the output shaft
of the motor 11, even if the motor 11 cannot be rotated in the reverse
direction because the worm wheel 12 and the rack 8 are brought into
engagement (locked with each other) when a starting torque is made
insufficient by the pull-up on the more core side, for example, then the
drive gear 12a is idled with respect to the rack 8 due to the similar
action mentioned above so that the drive gear 12a can be released from
being meshed with the rack 8. Therefore, the motor 11 can be avoided from
being disabled to rotate in the reverse direction.
Furthermore, while the protecting operation done by the optical pickup
device translating apparatus according to the present invention when the
optical pickup device is recklessly translated has been described so far,
the present invention is not limited thereto and can be operated as a
translating apparatus protecting mechanism that can protect the optical
pickup device translating apparatus when the optical pickup device is
translated at high speed during the access such as to find out a starting
portion of contents recorded on the optical disc, for example.
Moreover, while the worm wheel is used as the drive gear which is meshed
with the rack 8 to translate the optical pickup device 1 as described
above, the present invention is not limited thereto and other gear devices
may be used insofar as they can be rotated by the drive force of the motor
11 to thereby translate the rack 8.
While the motor base plate 13 and the mount 14 are coupled by means of the
shaft pins 17, 18 and the elliptic apertures 15, 16 as described above,
the present invention is not limited thereto and the two elliptic
apertures 15, 16 may be modified as a single aperture by connecting
respective outer edges with tangential lines with similar action being
obtained.
In addition, while the translating apparatus for an optical pickup device
is applied to the optical video disc player as described above, the
present invention is not limited thereto and may be applied to a wide
variety of other optical disc players such as a so-called compact disc
player or the like.
Having described a preferred embodiment of the invention with reference to
the accompanying drawings, it is to be understood that the invention is
not limited to that precise embodiment and that various changes and
modifications could be effected therein by one skilled in the art without
departing from the spirit or scope of the invention as defined in the
appended claims.
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